Connector for flexible transmission line

ABSTRACT

An electrical connector for flexible transmission lines of the coaxial type including an elongated probe of conductive metal having an end portion protruding insulatingly into the open end of a tubular center conductor of the coaxial line for a distance equal to an effective quarter wavelength of the energy to be transmitted by the line whereby an open circuit occurs at the engaged end of the probe and a low impedance junction is established between the circular end of the center conductor and the adjacent portion of the probe; and a coaxial, cylindrical shell of conductive metal having an internal shoulder clamped in direct metallic contact with a flanged end of the outer coaxial conductor.

United States Patent Philip H. Dyer Stow;

inventors Bernard Waters, Natick, Mass.

Appi. No. Filed Patented Assignee CONNECTOR FOR FLEXIBLE TRANSMISSIONPrimary Examiner-Herman Karl Saalbach Assistant Examiner-Paul L. GenslerAttorneys-Harold A. Murphy and Joseph D. Pannone LINE ABSTRACT: Anelectrical connector for flexible transmission 7 CHI, 2 Drum n lines ofthe coaxial type including an elongated probe of conductive metal havingan end portion protruding msulatmgly US. Cl. 333/97, into the open end fa tubular center conductor f the coaxial 174/88 line for a distanceequal to an effective quarter wavelength of II. Cl. H01!) 3/06 th rgy tobe transmitted by the line whereby an open Cl!- Fleld ofSelrch 333/96,97; m occurs at the engaged end f the probe and a low 174/ 75 pedancejunction is established between the circular end of thecenter conductorand the adjacent portion of the probe; References Cited and a coaxial,cylindrical shell of conductive metal having an UNITED STATES PATENTSinternal shoulder clamped in direct metallic contact with a 2,401,3446/1946 Espley 333/97X flanged end of the outer coaxial conductor.

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I7 I60 [704 I32 78 24 I /a 52 I36 .1 In a CONNECTOR FOR FLEXIBLETRANSMISSION LINE BACKGROUND OF THE INVENTION The invention hereindescribed was made in the course of 5 and under a contract orsubcontract thereunder, with the Department of the Army.

This invention is related generally to electrical connectors and isconcerned more particularly with high frequency connectors for flexibletransmission lines.

When microwave energy flows through a coaxial transmission line, theresulting electromagnetic fields impress an alternating voltage acrossthe annular space between the coaxial conductors and induce alternatingcurrents in the adjacent layers of the concentric conductors. Theinduced currents generate heat in the coaxial conductors and, therefore,represent power losses in the transmitted waves. These heat losses areproportional to the ohmic resistance of the conductor material and theimpedance ofthe interface connections in the transmission line.Consequently, the conductors are made of low resistivity material, suchas copper for example, and the impedance of each coupling'connection isminimized as much as possible. The center conductor of a coaxial linestabilizes at a higher temperature than the outer conductor due to thehigher current density in its reduced cross section. Therefore, theproblem of minimizing resistance between contacting surfaces is moreacute in the center conductor connections than between contactingsurfaces in the outer conductor. A problem of equal importance incoaxial lines is the concentration of electric field intensity aroundthe smaller surface of the center conductor, thereby establishing highvoltage gradients near the surface of the center conductor. When poorcontacting surfaces occur in the center conductor line, these highintensity electric fields build up a voltage potential between thecontacting surfaces. At sufficiently high voltage, air or other gaseousmedium between the poor contacting surfaces ionizes and arcing occursacross the intervening film of ionized gas. This burning processdeteriorates the contacting surfaces and opens the gap wide enough toconstitute an impedance discontinuity in the line. As a result,reflected waves are formed at the boundary of the discontinuity whichtravel back toward the input end of the line and, in doing so, passthrough increasingly stronger electric fields of the transmitted waves.When the reflected waves are in phase with the transmitted waves, thevoltage maxima of both waves combine and produce a corona dischargebetween the concentric conductors of the coaxial line. As a consequenceof this short circuit in the transmission line, the associatedtransmitting equipment may be seriously damaged. Therefore, lowresistance contacting surfaces in centerline connections are not onlyimportant to avoid heat losses but also to avoid corona dischargebetween the concentric conductors of the coaxial line.

Long transmission runs with many twists and bends are produced easilyand efficiently with the use of flexible or semirigid transmissionlines. However, the center conductor in a flexible or semirigid coaxialline operates at a higher temperature than the center conductor in arigid coaxial line, because the former requires dielectric supportingmeans at frequent intervals along the line in order to maintainconcentricity during flexing. Electromagnetic energy losses in thedielectric material of the supporting means produces heat which istransferred to the center conductor by means of conduction andconvection. This additional heat energy in the center conductor of aflexible or semirigid coaxial line contributes to the development ofpoor contacting surfaces in coupling connectors of the prior art.Usually, the center conductor junction in prior art connectors is formedby plugging the slotted bullet" of a male connector into the open end ofa center tube or jack in the female connector, thus providing a directmetal-to-metal contact. The slotted bullet comprises a tapered cylinderof resilient fingers which are compressed radially inward when thebullet is inserted into the tubular portion of the female connector.This connection between mating parts is made as tight as possible inorder to minimize the impedance of the connection and to reduce thepossiblity of field discontinuity. However, tolerances must be allowedon the dimensions of the mating parts because of the sliding engagementrequired by this type of connection.

It has been found that heat generated in the center conductor duringpulse transmission of microwave energy and subsequent cooling causes themating members of the connector to expand and contract. After a periodof time, the constant expansion and contraction causes the springfingers of the bullet to lose some resiliency and a small gap developsbetween one or more fingers and the rigid wall of the female tube.Flexing of the coaxial line also puts an additional stress on theresilient fingers of the bullet and contributes to the development ofthe gap between mating parts of the connector. As described above, theohmic resistance of the gap causes greater heat losses in thetransmitted waves and the high intensity electric fields surrounding thecenter conductor produce voltage breakdown across the gap. Thesubsequent arcing burns and pits the surfaces on each side of the gap,thereby widening the gap to form an impedance discontinuity in the line.The reflected waves produced at the boundary of this discontinuity leadto corona discharge and short circuiting of the transmission line.

SUMMARY OF THE INVENTION Accordingly, this invention provides a lowimpedance coupling connector which does not depend upon direct metalliccontact in the centerline connection. A dielectric bushing is fixedlymounted in the opening at one end of a tubular center conductor. Thebushing has an annular flange which abuts the circular end of the centerconductor and a longitudinal cavity having an open end centrally locatedin the flanged end of the bushing. An end portion of an elongated probeis inserted into the cavity and slidin'gly engages the inner diameter ofthe bushing. The engaged length of the probe reaches a maximum when anannular shoulder on the probe butts against the annular flange of thedielectric bushing, thus preventing metallic contact between theshoulder of the probe and the circular end of the center conductor. Theengaged length of the probe equals an effective quarter-wavelength inthe waveband to be transmitted by the coaxial line. Thus, an opencircuit occurs at the engaged end of the probe and a low impedancejunction is established between the circular end of the center conductorand the adjacent portion of the probe. Since the junction presents a lowimpedance to the transmitted waves, there is very little heat loss orvoltage buildup across the junction.

BRIEF DESCRIPTION OF THE DRAWING For a better understanding of thisinvention, reference is made to the accompanying drawing wherein:

FIG. 1 is a fragmentary longitudinal view, partly in axial section, of apreferred embodiment of this invention; and

FIG. 2 is a fragmentary longitudinal view, partly in axial section, ofanother preferred embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawingwherein like characters of reference designate like parts throughout theseveral views, there is shown in FIG. 1 one end of a flexibletransmission line 10 connected to a similar transmission line 12 bymeans of an intervening connector assembly 14. Transmission line 10comprises two coaxial conductors, a center conductor 16 and an outersurrounding conductor 18. Similarly, transmission 12 comprises a centerconductor 20 and an outer surrounding conductor 22. The respectiveconductors l6, 18, 20 and 22 are flexible tubes of helicallycorrugatedmetal, such as copper for example. Each of the respective centerconductors, 16 and 20, is centrally located and insulatingly supportedwithin the respective outer conductors, l8 and 22, by means of a helicalmembrane 24 of dielectric material, such as polyethylene for example.One longitudinal edge of the respective membranes 24 fits tightlyagainst the adjacent surface of the respective center conductors l6 and20. The other longitudinal edge of the respective membranes 24 isprovided with transverse slots 26. which interlock with the adjacentcorrugated walls of the respective outer conductors l8 and 22.

Connector assembly 14 comprises a male connector 32 mated to a femaleconnector 34. Connector 32 includes an outer shell 36 which is clampedto outer conductor 18, a dielectric bushing 38 which is mounted in anopen end of center conductor 16 and a cylindrical probe 40 which has anend portion disposed in dielectric bushing 38. Outer shell 36 comprisesa metallic nut 42 having internal threads 44 adjacent one end and arestricted neck portion 46 at the opposite end which slides over themajor diameter of outer conductor 18. An internal shoulder 48 is formedin nut 42 where the neck portion 46 joins the larger diameter portion ofnut 42. A cast collet 50 of light weight metal, such as aluminum forexample, is provided with a helically corrugated inner surface whichthreads loosely onto the corrugated outer surface of conductor 18. Anenlarged end 52 of collet 50 provides an annular bearing surface forthe'internal shoulder 48 of nut 42. The circular end of outerconductor.l8 is flared radially outward to form anannularflange 54 whichabuts the adjacent end 56 of collet 50. A cylinder housing 60 ofconductive metal, such as bronze for example, is provided with arestricted portion 62 which forms an internal shoulder 64. The

larger diameter portion of housing 60 slides over the outer surface ofcollet 50 until internal shoulder 64 butts against the flange 54 ofconductor 18. External threads 66 adjacent the larger diameter end ofhousing 60 are engaged by the internal threads 44 of nut 42. When nut 42is rotated, internal shoulder 48 bears against the adjacent end 52 ofcollet 50 and presses the opposite end 56 against flange 54. Sincecollet 50 is threaded loosely onto conductor 18, there is sufficientplay between the helical corrugations of collet 50 and those ofconductor 18 to allow slight axial movement of collet 50. As a result,flange 54 is forced against the internal shoulder 64 of housing 60, thuseffecting a direct metal-to-metal contact between conductor 18 and outershell 36. The opposite end of housing 60 terminates in an annularcoupling flange 68.

Connector 32 also includes a bushing 38 of dielectric material, such aspolytetrafluoroethylene for example, which is fixedly mounted in an openend of center conductor 16, as by journaling for example. Bushing 38 isprovided with an annular flange 72 which abuts the circular end ofcenter conductor l6 and a longitudinal cavity 74 having a circularopening disposed in the flanged end of bushing 38. Connector 32 alsoincludes a cylindrical probe 40 of conductive metal, such as copper forexample. A reduced diameter portion 78 at one end of probe 40 forms anannular shoulder 80 where it joins a larger diameter portion 82 of probe40. The reduced diameter 78 of probe 40 slidingly engages the innerdiameter of bushing 38 when inserted into cavity 74. The maximum engagedlength of the reduced portion 78 is reached when the shoulder 80 ofprobe 40 butts against the flange 72 of bushing 38. Thus, the shoulder80 prevents the engaged end 84 of probe 40 from touching the bottom ofcavity 74 and the flange 72 prevents the shoulder 80 from contacting thecircular end of the center conductor 16. Usually, shoulder 80 is spacedslightly away from flange 72 to allow for thermal expansion duringtransmission and a possible buildup of manufacturing tolerances. Whentransmitted energy flows through line 10, the annular space between thecenter conductor 16 and the engaged end 84 of probe 40 represents aninfinite impedance to the transmitted waves. Therefore, the electricfield and the resulting voltage potential reach a maximum value in thisregion of the center conductor line. However, an effectivequarterwavelength back, the annular space between the circular end ofthe center conductor 16 and the adjacent surface of the probe 40represent a low impedance to the transmitted waves. Therefore, themagnetic field and resulting current density reach a maximum value inthis low impedance region of the center conductor line. Because of thelow impedance, heat losses will be low also. Since the electric fieldintensity reaches a minimum value at the low impedance junction, voltagebreakdown and arcing will not occur between the circular end of centerconductor 16 and the adjacent portion of probe 40. Thus, the connector34 shown in FIG. 1 avoids the problems encountered when using the directmetallic pressure connections of the prior art.

The dielectric material of bushing 38 and the capacitance between probeend 84 and the bottom of cavity 74 both have the electrical effect ofincreasing the engaged length of probe 40. In order to offset thiselectrical effect, the engaged length of probe 40 is made physicallyshorter than would be required if it were surrounded by free space.Thus, the engaged length of probe 40 is referred to as an effectivequarterwavelength, because it has the same electrical effect as a freespace quarter-wavelength. Transverse motion of center conductor 16during flexing of the line 10 does not distort the concentricity becausethe engaged length of probe 40 is surrounded by the dielectric bushing38. However, flexing of line 10 may cause slight longitudinal movementof the center conductor 16 whereby the flange 72 of bushing 38 movesaway from the shoulder and the engaged length of probe 40 decreases. Inthis case, the resultant engaged length of probe 40 equals an effectivequarter-wavelength for another frequency in the transmitted waveband.The resultant junction between the circular end of center conductor 16and the then adjacent portion of probe 40 will still represent a lowimpedance path to the entire band of transmitted waves.

The oppositeend portion of probe 40 may be terminated in any mannerrequired for mating with a connecting device. For connecting twotransmission lines, as shown in FIG. 1, the opposite end portion ofprobe 40 is provided with a reduced diameter similar to end portion 78and forms an annular shoulder 92 where it meets the larger diameterportion 82 of probe 40. Female connector 34 includes a dielectricbushing 94 which is fixedly mounted in an open end of center conductor20. Bushing 94 is provided with an annular flange 96 which abuts thecircular end of center conductor 20 and a longitudinal cavity 98 havingan open end disposed in the flanged end of bushing 94. The innerdiameter of bushing 94 slidingly engages the reduced diameter portion 90of probe 40 when the latter is inserted into cavity 98. The maximumengaged length of the reduced portion 90 is reached when flange 96 ofbushing 94 butts against the shoulder 92 of probe 40. Thus, shoulder 92prevents the end 100 of reduced diameter portion 90 from touching thebottom of cavity 98 and the flange 96 prevents the shoulder 92 fromcontacting the circular end of center conductor 20. However, inpractice, shoulder 92 is spaced slightly away from flange 96- to allowfor thermal expansion during transmission and a possible buildup ofmanufacturing tolerances. When transmitted energy flows through line 10and connector assembly 14, the annular space between the end 100 ofprobe 40 and the center conductor 20 represents an infinite impedance tothe transmitted waves. An effective quarter-wavelength back, the annularspace between the circular end of center conductor 18 and the adjacentsurface of the probe 40 represents a low impedance path to thetransmitted waves. Thus, a low impedance connection is achieved betweenthe probe 40 and the center conductor 20 which results in low heat lossand avoids the buildup of high voltages across the junction thus formed.Female connector 34 also includes an outer shell 102 having a metallicnut 104 with a restricted neck portion 106 and an internal shoulder 108.Threads 110 are disposed on the inner surface of nut 104 adjacent thelarger diameter end thereof. A metallic collet 112 is provided with ahelically corrugated inner surface which threads loosely onto the outersurface of conductor 4 22. An enlarged end 114 of collet 112 provides anannular bearing surface for the internal shoulder 108 of nut 104. Thecircular end of conductor 22 is flared radially outward to form anannular flange 116 which abuts an adjacent end 118 of collet 112. Acylindrical housing 120 is provided with a restricted portion 126 whichforms an internal shoulder 124. The en larged diameter portion ofhousing 120 slides over the outer surface of collet 112 until theinternal shoulder 124 butts against flange 116 of conductor 22. Externalthreads 128 are provided adjacent the larger diameter end of housing120,

which threads are engaged by the internal threads 110 of nut 104. Whennut 104 is rotated, the internal shoulder 108 bears against the adjacentend of collet 112 and presses the opposite end 118 against flange 116 ofconductor 22. Thus, flange 116 is forced against the internal shoulder124 of housing 120 and a direct metal-to-metal contact is achievedbetween outer conductor 22 and the shell 102. The restricted portion 126terminates at one end of housing 120 in a coupling flange 130 whichinterfaces with the coupling flange 68 of connector 32. An annularprojection 132 on the interfacing surface of flange 68 engages anannular recess 134 in the interfacing surface of flange 130, thusproviding alignment during coupling. An 0- ring 136 is disposed incooperating grooves 138 and 140 in the adjacent surfaces of therespective flanges 68 and 130 to provide a pressure-tight joint betweenthe respective housings 60 and 120. Flanges 68 and 130 are coupled witha V-band clamping ring 142 of the conventional type which compressesO-ring 136 and brings the interfacing surface of flange 68 into directmetallic contact with the interfacing surface of flange 130. Thus,shells 36 and 102 form an outer metallic casing which has a portion inmetallic contact with outer conductor 18 and another portion in metalliccontact with outer conductor 22. Consequently, a direct current path is,produced between outer conductor 18 of transmission line and outerconductor 22 of transmission line 12.

FIG. 2 illustrates how the male connector 32 connects flexibletransmission line 10 to an electrical component 150. The component 150is provided with an outer rigid tube 152 having a flange 154 which issecured to component 150 by conventional means, as by bolts 156 forexample. The opposite end 9f tube 152 terminates in a coupling flange158 which interfaces with coupling flange 68 of outer shell 36. Theannular recess 160 in the interfacing surface of flange 158 receives theannular projection 132 of flange 68 for alignment purposes duringcoupling. An O-ring 136 is disposed in cooperating grooves 162 and 138in the adjacent surfaces of respective flanges 68 and 158 whereby apressure-tight joint is achieved during coupling. Flange 68 is coupledto flange 158 by means of a conventional V-band clamping ring. 142 whichcompresses O-ring 136 and brings the interfacing surface of flange 68into direct metallic contact with the interfacing surface of flange 158.A rigid center conductor 170 projects out of electrical component 150and is insulatingly supported within rigid tube 152 by means ofdielectric bead 172. Center conductor 170 comprises a hollow tube ofconductive material, such as copper for example, and a bushing 174 ofdielectric material, such as polytetrafluoroethylene for example, isfixedly mounted in the open end thereof. Bushing 174 is provided with anannular flange 176 which abuts the circular end of center tube 170 and alongitudinal cavity which is similar to cavity 74 in bushing 38 ofconnector 32. The reduced diameter end portion 90 of probe 40 slidinglyengages the inner diameter of bushing 174 when it is inserted into thelongitudinal cavity of bushing 174. The maximum engaged length of thereduced diameter portion 90 is reached when shoulder 92 abuts the flange176 of bushing 174. Thus, shoulder 92 prevents the end of reduceddiameter portion 90 from touching the bottom of the longitudinal cavityin bushing 174, and the flange 176 of bushing 174 prevents the shoulder92 from contacting the circular end of center tube 170. Preferably,shoulder 92 is spaced slightly away from flange 176 to allow for thermalexpansion during transmission and a possible buildup of manufacturingtolerances. When transmitted energy flows through line 10 and connector32, the annular space between the end of reduced diameter portion 90 andthe surrounding portion of center tube 170 represents an infiniteimpedance to the transmitted waves. An effective quarter-wavelengthback, the annular space between the circular end of center tube 170 andthe adjacent surface of reduced diameter portion 90 represents a lowimpedance to the transmitted waves. Thus, a low impedance connection isachieved between the probe 40 and the center tube 170 which results inlow heat loss and avoids the buildup of high voltages across thejunction thus formed. The annular space between center conductor 16 andouter conductor 18 does not have the same physical dimensions as theannular space in a rigid coaxial line because of the corrugated wallsand the dielectric membrane 24. However, transmission line 10 isdesigned and fabricated to provide the same characteristic impedance asan equivalent rigid coaxial line, 50 ohms for example. The annular spacebetween the larger diameter portion 82 of probe 40 and the innerdiameter of restricted portion 62 is equal dimensionally to theequivalent annular space in the rigid coaxial line and provides the samecharacteristic impedance, such as 50 ohms for example. Therefore,transmission line 10 and connector 32 are impedance matched to connectdirectly to a standard rigid coaxial line, as shown in FIG. 2.

Thus, there has been disclosed herein a novel connector for flexibletransmission lines' having an outer shell which is clamped in directmetallic contact with one conductor of the transmission line and aninner probe having a portion thereof disposed in spaced, parallelrelationship with a portion of the other conductor of the transmissionline for a distance equal to an effective quarter-wavelength of theenergy to be trans mitted by the flexible line. Thus, an open circuitoccurs between the end of the probe and the opposing surface of theflexible center conductor; and a low impedance junction occurs betweenthe end of the flexible center conductor and the opposing surface of theprobe. Although a corrugated type of flexible transmission line has beenillustrated herein, the connector of this invention is applicable toother flexible types of transmission lines, such as a bellows type forexample. Furthermore, the center conductor of the flexible transmissionline need not be hollow but may be filled with a flexible dielectricmaterial and have hollow end portions, for example. Also, the dielectricbushing fixedly mounted in the open end of the center conductor could bereplaced by a dielectric sleeve having a longitudinal bore open at bothends. These and other modifications of this type are within the spiritand scope of this invention and, as such, are intended to be included inthe claims appended hereto.

We claim: I

1. In combination, a male connector and a flexible coaxialtransmissionline comprising:

a first flexible conductor having a hollow end portion;

a second flexible conductor surrounding said first conductor anddisposed in spaced, parallel relationship therewith;

a dielectric cylinder fixedly mounted in said hollow end portion of thefirst conductor and having a longitudinal bore disposed therein, saidbore having an opening in the end of said cylinder adjacent the end ofthe first conductor:

an elongated conductive probe having an end portion slidably engaged insaid bore, being mounted for slidable movement within said bore inresponse to flexing of said line, and extended in parallel relationshipwith said end portion of the first conductor for a distance equal to aquarter-wavelength of one frequency to be transmitted by the line;

a tubular housing insulatingly surrounding a portion of said probe andhaving a portion disposed in abutting relationship with an end portionof said second conductor; and

means for clamping said abutting portions of the housing and the secondconductor into direct metallic contact with one another.

2. In combination, a male connector and a flexible coaxial transmissionline as set forth in claim 1 wherein said dielectric cylinder is abushing and said longitudinal bore is a cavity closed at the end of thebushing remote from the end of the first conductor.

3. In combination, a male connector and a flexible coaxial transmissionline comprising:

a first, tubular, flexible conductor having an open end;

a second, tubular, flexible conductor surrounding said first conductorand disposed in spaced concentric relationship therewith;

a dielectric bushing fixedly mounted in the open end of the firstconductouand having a longitudinal cavity therein, said cavity having anopen end in the end of the bushing disposed adjacent the end of thecenter conductor;

an elongated probe having an end portion slidably engaged in 'saidcavity, being mounted for slidable movement within said cavity inresponse to flexing of said line, and a portion of said end portionextended in parallel relationship with an end portion of the firstconductor for a distance predetermined to be equal to aquarterwavelength of one frequency to be transmitted through the coaxialtransmission line;

a tubular shell insulatingly surrounding a portion of said probe andhaving a portion thereof clamped to an abutting end portion of saidouter conductor; and

means for clamping said portion of the shell into direct metalliccontact with said abutting end portion of the outer conductor.

4. In combination, a male connector and a flexible coaxial transmissionline comprising:

a first, tubular, flexible conductor having an open end;

a second, tubular, flexible conductor disposed in spaced concentricrelationship with said first conductor and terminating at one'end in aradially-extending flange;

a dielectric bushing fixedly mounted in the open end of the firstconductor, said bushing including an annular flange disposed in abuttingrelationship with the end of the first conductor and a longitudinalcavity having an open end in the flanged end of the bushing;

an elongated probe having an end portion slidably engaged in saidcavity, being mounted for slidable movement within said cavity inresponse to flexing of said line, the length of said end portion beingsubstantially equal to the thickness of the flange of the bushing plus aquarterwavelength of one frequency in the waveband to be transmittedthrough said line, said probe further having an oppositely directed endportion;

a tubular shell disposed in surrounding, spaced relationship with aportion of said probe and having an internal shoulder disposed inabutting relationship with said flanged end of said outer conductor andan opposite end having a flange disposed in abutting relationship with asimilar flange on a connecting device; and

means for clamping said flanged end of the outer conductor into directmetallic contact with said internal shoulder of the shell.

5. In combination, a connector assembly and two, flexible,

coaxial transmission lines comprising:

a first, flexible, center conductor insulatingly disposed within a firstflexible concentric conductor, said first center and concentricconductors having adjacent hollow end portions;

a second, flexible, center conductor insulating disposed within asecond, flexible, concentric conductor, said secondcenter and concentricconductors having adjacent hollowend portions;

said first center and concentric hollow end portions disposed adjacentsaid second center and concentric hollow end portions;

a first dielectric cylinder interfitted in the hollow end portion of thefirst center conductor and having a longitudinal bore, said bore havingan opening in the end of said cylinder adjacent the end of the firstconductor;

a second dielectric cylinder interfitted in the hollow end portion ofthe second center conductor and having a longitudinal bore, said borehaving an opening in the end of said cylinder adjacent the end of thesecond conductor;

an elongated probe having one end portion slidably engaged in said boreof the first dielectric cylinder, being mounted for slidable movementwithin said bore in response to flexing of said first center conductor,and supported in spaced, parallel relationship with an end portion ofthe first center conductor and an opposite end portion slidably engagedin said bore of the second dielectric cylinder, being mounted forslidable within said bore in response to flexing of said second centerconductor, and supported in spaced, parallel relationship with an endportion of. the second center conductor, the end portions of the probeand center conductors being equal to an effective quarter-wavelength ofone frequency to be transmitted through said transmission lines;

a tubular casing disposed in surrounding spaced relationship with saidprobe and having a portion'disposed in abutting relationship with anadjacent end portion of the first concentric conductor and an oppositeend portion disposed in abutting relationship with an adjacent endportion of the second concentric conductor; and

means for clamping said abutting portions of the casing into directmetallic contact with said end portion of the respective first andsecond concentric conductors of the respective transmission lines.

6. In combination, a connector assembly and two flexible coaxialtransmission lines comprising:

a first, tubular, center conductor made of flexible material andinsulatingly disposed within a first, tubular concentric conductor alsomade of flexible material;

a second, tubular, center conductor made of flexible material andinsulatingly disposed within a second tubular conductor also made offlexible material;

said first center and concentric conductors having respective endportions axially aligned with respective end portions of said secondcenter and concentric conductors;

a first dielectric bushing fixedly mounted in said end portion of thefirst center conductor and having a longitudinal cavity disposedtherein, said cavity having an open end located in the exposed end ofthe bushing;

a second dielectric bushing fixedly mounted in said end portion of thesecond center conductor, and having a longitudinal cavity disposedtherein, said cavity having an open end in the exposed end of saidsecond dielectric bushing;

an elongated probe having an end portion slidably disposed in saidcavity of the first dielectric bushing, being mounted for slidablemovement within said cavity in response to flexing of said first centerconductor, and surrounded by said end portion of the first centerconductor, and an opposite end portion slidably disposed in said cavityof the second dielectric bushing, being mounted for slidable movementwithin said cavity in response to flexing of said second centerconductor, and surrounded by said end portion of the second centerconductor, said respective end portions of the probe and centerconductors each being equal to a quarter-wavelength of one of thefrequencies to be transmitted by the respective transmission lines;

a first tubular shell disposed in surrounding spaced relationship with aportion of said probe and having an end portion surrounding an adjacentend portion of the first concentric conductor and an opposite endportion;

a second tubular shell disposed in surrounding spaced relationship withanother portion of the probe and having an end portion surrounding anadjacent end portion of the second concentric conductor in said othertransmission line and an opposite end portion interlocked with saidopposite end portion of the first shell; and

means for clamping said respective end portions of the first and secondshells into direct metallic contact with the respective end portions ofthe respective first and second concentric conductors in the respectivetransmission lines.

7. In combination, a connector assembly and two flexible coaxialtransmission lines comprising:

a first, tubular, center conductor made of flexible material andinsulatingly disposed within a first, tubular concentric conductor vmadeof flexible material and having a radial flange on one end thereof;

a second tubular, center conductor made of flexible material andinsulatingly disposed within a second tubular concentric conductor madeof flexible material, and having a radial flange on one end thereof;

said first centerand concentric conductors having respective endportions axially aligned with respective end portions of said secondcenter and concentric conductors;

a first dielectric bushing interfitted in said end portion of the firstcenter conductor and having an annular flange disposed in abuttingrelationship with the circular end of said first center conductor and alongitudinal cavity disposed therein having an open end in the flangedend of said first bushing;

a second dielectric bushing interfitted in said end portion of thesecond center conductor and having an annular flange disposed inabutting relationship with the circular end of second center conductorand a longitudinal cavity disposed therein having an open end in theflange end of said second bushing; I

an elongated probe having an end portion slidably disposed in saidcavity of the first bushing, being mounted for slidable movement withinsaid cavity in response to flexing of said first center conductor, andsurrounded by said end portion of the first center conductor in said oneline, and

an opposite end portion slidably disposed in said cavity of the secondbushing, being mounted for slidable movement within said cavity inresponse to flexing of said second center conductor, andsurroundedbysaid end portion of the second center conductor, said respective endportions of the probe and center conductors each being equal to aquarter-wavelength of one of the frequencies to be transmitted throughthe respective transmission lines;

a first tubular shell disposed in surrounding spaced relationship with aportion of said probe and having a portion thereof abutting said flangedend of the first concentric conductor and an oppositely disposed endhaving an annular coupling flange; i

a second tubular shell disposed in surrounding spaced relationship witha portion of said probe and having a portion thereof abutting saidflanged end of the second concen' tric conductor and an oppositelydisposed end having an annular coupling flange clamped into directmetallic contact with said coupling flange of the first shell; and

means for clamping said respective abutting portions of the respectiveshells into direct metallic contact with said respective flanged ends ofthe first and second concentric conductors in the respectivetransmission lines.

" NETED STATES PATENT OFFICE CEATEI'. ICATL 6i CORHECTIUN Patent No. 3,568, 111 Dated March 2, 1971 Invent0r(s) Phillip H. Dyer and BernardWaters It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

Column 8, line 5 (Claim 5) After "slidable" insert --movement-- Signedand sealed this Zlrth day of August 1971.

(SEAL) Attest:

EDWARD M.FLETGHER,JR. WILLIAM E. SGHUYLER, J'R Attesting OfficerCommissioner of Patents

1. In combination, a male connector and a flexible coaxial transmissionline comprising: a first flexible conductor having a hollow end portion;a second flexible conductor surrounding said first conductor anddisposed in spaced, parallel relationship therewith; a dielectriccylinder fixedly mounted in said hollow end portion of the firstconductor and having a longitudinal bore disposed therein, said borehaving an opening in the end of said cylinder adjacent the end of thefirst conductor: an elongated conductive probe having an end portionslidably engaged in said bore, being mounted for slidable movementwithin said bore in response to flexing of said line, and extended inparallel relationship with said end portion of the first conductor for adistance equal to a quarter-wavelength of one frequency to betransmitted by the line; a tubular housing insulatingly surrounding aportion of said probe and having a portion disposed in abuttingrelationship with an end portion of said second conductor; and means forclamping said abutting portions of the housing and the second conductorinto direct metallic contact with one another.
 2. In combination, a maleconnector and a flexible coaxial transmission line as set forth in claim1 wherein said dielectric cylinder is a bushing and said longitudinalbore is a cavity closed at the end of the bushing remote from the end ofthe first conductor.
 3. In combination, a male connector and a flexiblecoaxial transmission line comprising: a first, tubular, flexibleconductor having an open end; a second, tubular, flexible conductorsurrounding said first conductor and disposed in spaced concentricrelationship therewith; a dielectric bushing fixedly mounted in the openend of the first conductor, and having a longitudinal cavity therein,said cavity having an open end in the end of the bushing disposedadjacent the end of the center conductor; an elongated probe having anend portion slidably engaged in said cavity, being mounted for slidablemovement within said cavity in response to flexing of said line, and aportion of said end portion extended in parallel relationship with anend portion of the first conductor for a distance predetermined to beequal to a quarter-wavelength of one frequency to be transmitted throughthe coaxial transmission line; a tubular shell insulatingly surroundinga portion of said probe and having a portion thereof clamped to anabutting end portion of said outer conductor; and means for clampingsaid portion of the shell into direct metallic contact with saidabutting end portion of the outer conductor.
 4. In combination, a maleconnector and a flexible coaxial transmission line comprising: a first,tubular, flexible conductor having an open end; a second, tubular,flexiblE conductor disposed in spaced concentric relationship with saidfirst conductor and terminating at one end in a radially extendingflange; a dielectric bushing fixedly mounted in the open end of thefirst conductor, said bushing including an annular flange disposed inabutting relationship with the end of the first conductor and alongitudinal cavity having an open end in the flanged end of thebushing; an elongated probe having an end portion slidably engaged insaid cavity, being mounted for slidable movement within said cavity inresponse to flexing of said line, the length of said end portion beingsubstantially equal to the thickness of the flange of the bushing plus aquarter-wavelength of one frequency in the waveband to be transmittedthrough said line, said probe further having an oppositely directed endportion; a tubular shell disposed in surrounding, spaced relationshipwith a portion of said probe and having an internal shoulder disposed inabutting relationship with said flanged end of said outer conductor andan opposite end having a flange disposed in abutting relationship with asimilar flange on a connecting device; and means for clamping saidflanged end of the outer conductor into direct metallic contact withsaid internal shoulder of the shell.
 5. In combination, a connectorassembly and two, flexible, coaxial transmission lines comprising: afirst, flexible, center conductor insulatingly disposed within a firstflexible concentric conductor, said first center and concentricconductors having adjacent hollow end portions; a second, flexible,center conductor insulating disposed within a second, flexible,concentric conductor, said second center and concentric conductorshaving adjacent hollow end portions; said first center and concentrichollow end portions disposed adjacent said second center and concentrichollow end portions; a first dielectric cylinder interfitted in thehollow end portion of the first center conductor and having alongitudinal bore, said bore having an opening in the end of saidcylinder adjacent the end of the first conductor; a second dielectriccylinder interfitted in the hollow end portion of the second centerconductor and having a longitudinal bore, said bore having an opening inthe end of said cylinder adjacent the end of the second conductor; anelongated probe having one end portion slidably engaged in said bore ofthe first dielectric cylinder, being mounted for slidable movementwithin said bore in response to flexing of said first center conductor,and supported in spaced, parallel relationship with an end portion ofthe first center conductor and an opposite end portion slidably engagedin said bore of the second dielectric cylinder, being mounted forslidable within said bore in response to flexing of said second centerconductor, and supported in spaced, parallel relationship with an endportion of the second center conductor, the end portions of the probeand center conductors being equal to an effective quarter-wavelength ofone frequency to be transmitted through said transmission lines; atubular casing disposed in surrounding spaced relationship with saidprobe and having a portion disposed in abutting relationship with anadjacent end portion of the first concentric conductor and an oppositeend portion disposed in abutting relationship with an adjacent endportion of the second concentric conductor; and means for clamping saidabutting portions of the casing into direct metallic contact with saidend portion of the respective first and second concentric conductors ofthe respective transmission lines.
 6. In combination, a connectorassembly and two flexible coaxial transmission lines comprising: afirst, tubular, center conductor made of flexible material andinsulatingly disposed within a first, tubular concentric conductor alsomade of flexible material; a second, tubular, center conductor made offlexible material and insulatingly disposEd within a second tubularconductor also made of flexible material; said first center andconcentric conductors having respective end portions axially alignedwith respective end portions of said second center and concentricconductors; a first dielectric bushing fixedly mounted in said endportion of the first center conductor and having a longitudinal cavitydisposed therein, said cavity having an open end located in the exposedend of the bushing; a second dielectric bushing fixedly mounted in saidend portion of the second center conductor, and having a longitudinalcavity disposed therein, said cavity having an open end in the exposedend of said second dielectric bushing; an elongated probe having an endportion slidably disposed in said cavity of the first dielectricbushing, being mounted for slidable movement within said cavity inresponse to flexing of said first center conductor, and surrounded bysaid end portion of the first center conductor, and an opposite endportion slidably disposed in said cavity of the second dielectricbushing, being mounted for slidable movement within said cavity inresponse to flexing of said second center conductor, and surrounded bysaid end portion of the second center conductor, said respective endportions of the probe and center conductors each being equal to aquarter-wavelength of one of the frequencies to be transmitted by therespective transmission lines; a first tubular shell disposed insurrounding spaced relationship with a portion of said probe and havingan end portion surrounding an adjacent end portion of the firstconcentric conductor and an opposite end portion; a second tubular shelldisposed in surrounding spaced relationship with another portion of theprobe and having an end portion surrounding an adjacent end portion ofthe second concentric conductor in said other transmission line and anopposite end portion interlocked with said opposite end portion of thefirst shell; and means for clamping said respective end portions of thefirst and second shells into direct metallic contact with the respectiveend portions of the respective first and second concentric conductors inthe respective transmission lines.
 7. In combination, a connectorassembly and two flexible coaxial transmission lines comprising: afirst, tubular, center conductor made of flexible material andinsulatingly disposed within a first, tubular concentric conductor madeof flexible material and having a radial flange on one end thereof; asecond, tubular, center conductor made of flexible material andinsulatingly disposed within a second tubular concentric conductor madeof flexible material, and having a radial flange on one end thereof;said first center and concentric conductors having respective endportions axially aligned with respective end portions of said secondcenter and concentric conductors; a first dielectric bushing interfittedin said end portion of the first center conductor and having an annularflange disposed in abutting relationship with the circular end of saidfirst center conductor and a longitudinal cavity disposed therein havingan open end in the flanged end of said first bushing; a seconddielectric bushing interfitted in said end portion of the second centerconductor and having an annular flange disposed in abutting relationshipwith the circular end of second center conductor and a longitudinalcavity disposed therein having an open end in the flange end of saidsecond bushing; an elongated probe having an end portion slidablydisposed in said cavity of the first bushing, being mounted for slidablemovement within said cavity in response to flexing of said first centerconductor, and surrounded by said end portion of the first centerconductor in said one line, and an opposite end portion slidablydisposed in said cavity of the second bushing, being mounted forslidable movement within said cavity in response to flexing of saidsecond center conDuctor, and surrounded by said end portion of thesecond center conductor, said respective end portions of the probe andcenter conductors each being equal to a quarter-wavelength of one of thefrequencies to be transmitted through the respective transmission lines;a first tubular shell disposed in surrounding spaced relationship with aportion of said probe and having a portion thereof abutting said flangedend of the first concentric conductor and an oppositely disposed endhaving an annular coupling flange; a second tubular shell disposed insurrounding spaced relationship with a portion of said probe and havinga portion thereof abutting said flanged end of the second concentricconductor and an oppositely disposed end having an annular couplingflange clamped into direct metallic contact with said coupling flange ofthe first shell; and means for clamping said respective abuttingportions of the respective shells into direct metallic contact with saidrespective flanged ends of the first and second concentric conductors inthe respective transmission lines.